This week's demo is all about particles falling through viscous fluid. In this case, we'll be dropping some steel ball bearings into corn syrup.
The fluid behavior in the video is mostly laminar - the size of the sphere and viscosity of the fluid don't produce any separation of the flow or turbulence. I wrote a bit about Stoke's Law in a previous post. For particles falling through water, the maximum particle size that will exhibit laminar behavior is around 0.1mm. For the steel spheres, we didn't manage to see any flow separation - but did see interference with the container's edge with really big spheres.
A graph of the resulting velocity shows a nice linear relationship between the square of the sphere's radius and its terminal velocity (except for the largest spheres, where interference with the container's edge slowed them down.